• LTC1968 Output Noise


    I can't make sense of the output noise specs of the LTC1968 RMS-to-DC converter.

    The datasheet (graph 1967 G18 and 1968 G19) shows something called "PEAK OUTPUT NOISE".

    However, I can't figure out how to use this information; What…

  • RE: RMS Current Control Based on LTC1968

    Hi aliaykan:  The LTC6226 seems like overkill on the bandwidth compared to the LTC1968 and LT1782.  Also, it has high bias current which will compromise the accuracy of the LTC1968.  For a gain of 2, I would recommend another LT1782.

    Regarding the speed…

  • Driving LTC1968 Fully Differential


    I see that LTC1968 RMS to DC converter has a differential input that can be driven in single ended or differential mode and DC or AC coupled.

    If I drive the input with a fully differential op-amp, do I need to place an RC filter between the op-amp…

  • LTC1968 and AC coupled input

    I am simulating the LTC1968 with an AC coupled input.

    When I run a transient simulation with external DC voltages at 0 or V2 = 0 initial condition (see schematic), I see that V2 node takes tens of seconds to reach 2.5 V. As a consequence, the output of…

  • LTC1967 / LTC1968 input common mode voltage setting


    The LTC1966 / LTC1967 / LTC1968 inputs can be AC or DC coupled. In single ended AC coupling mode, the switched capacitor action sets the input common mode voltage to the desired value (DC value of IN1 reaches V+/2, in figure 9b; IN2 reaches V_DC in…

  • RE: RMS Detection is Frequency Dependent?

    This is not my usual beat, but if I may jump in, I think the two parts mentioned are not spec'd for frequencies below 10MHz in the case of AD5904 and 100MHz for ADL5511 and thus might not function well down there. Although both datasheets say "DC to 6…

  • Optically-coupled differential output device attenuator for LTC1986 input

    I want to connect the differential output of a TLP7920 optically-coupled isolation amplifier to an LTC1968 for RMS measurement.

    My signal frequencies will be in the 8kHz-15kHz range.

    The Toshiba TLP7920 output differential output can range from +2.5V…


    Thanks for the tag, FormerMember!

    Hi David!

    I am *actually* not Jim Staley, the signal conditioning applications engineering legend, I'm James Staley the industrial power systems guy. Confusing, I know... It was easy to tell us apart because Jim…

  • RE: AD8436: several questions about deployment

    Hello EVC,

    1. The AD8436 error does vary with input level. These types of rms-dc are based on a log-antilog approach, which is constrained by the supply voltage and input level. The 300mV for this part is the test voltage as you noted above.

    2. The…